Auto tranny problem (A340E)

[steeven001]

Okay well my 89 Cressida with 210 000kms on it has a slight problem with the tranny. It's a 7mge with a A340E automatic transmission.

Sometimes it does not lockup the torque converter in overdrive and other times it does it fine. So I'll be spinning an extra like 500rpm at highway speeds and gas milage is going down when it doesn't lock up.

Fluid is in really good condition I flushed it like 40 000kms ago and I drain and fill with every oil change. Using Toyota Type IV ATF.

Any ideas? Is there a something that controls torque converter lockup?

 

[IJ.]

There is a temp component to the lockup so if there's anything wrong with the Sender to the ECU it won't lock (needs to be 60c+)

 

[3p141592654]

TIV is a JWS 3309 spec oil. I know for a fact that Dexron III in a tranny requiring JWS 3309 (like recent Aisin 5 and 6 speeds ) will cause failure in short order.

Whether it is backwards compatible I don't know, but I would stick with Dexron III for the A340E unless you are sure TIV is recommended as a substitute for Dexron III.

http://avlube.com/mobilatf3309.html

 

[steeven001]

I know it doesn't lock up until coolant is hot enough but even when the engine is at operating temperature it doesn't lock up sometimes.

Like heres an example I drive about 100kms a day 50kms each way. The highway is about 20kms from my house so by the time I get there the car is as warm as its going to get. I jump on the highway I get up to a 100kmh torque converter is locked up engine is spinning at 2200rpm. I hit traffic I slow down to 60kmh and speed back up to 100kmh and it no longer wants to lockup back and I'm spinning at 2500-2600rpm now.

It's really random sometimes it works sometimes it doesn't.

And about the fuild I've searched about fluid and seems as those both Dexron III or T-IV is fine and that T-IV helps with shuddering. This problem started to happen not too long ago as I've been using T-IV for 40 000kms now and I'm not sure what was in the tranny before that as I bought the car used.

 

[IJ.]

And a faulty temp sender/wiring/bad connector would cause that......:nono:

Man it's hard to help you guys that "know things"

 

[steeven001]

Sorry if I sounded like the know it all type.

I've checked my coolant temp sensor for resistance and it's good from cold start up to fully warmed up. I've checked the resistance at the ecu connector and its pretty damn close to the reading at the sensor. So I would say the coolant temperature sensor is in working order.

Unless the transmission uses another temp sensor that I am not aware of?

 

[IJ.]

Trans codes?

 

[steeven001]

No codes.

Possible for it to be a sticky solenoid valve for it to happen randomly?

 

[IJ.]

Just to be sure I'm talking about Trans Codes NOT ECU codes?

Anything is possible I guess but the stock solenoids are big dumb things that should be pretty reliable.

 

[Kckazdude]

Test the TPS. A 'flat spot' on the contacts will cause this exact issue.

 

[steeven001]

Just to clarify when checking for tranny codes the tsrm says jump terminals Tt and E1 I do that and my o/d light does not flash at all it stays off. So what's going on here?
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=AT&P=14

If I jump terminals Te1 and E1 my o/d light and check engine light are flashing constantly meaning no codes. Does this way even work for tranny codes too?

I'll check the TPS out tomarrow. Am I testing for voltage like in the tsrm or are you talking about something physical when you say flat spot?

 

[Kckazdude]

I'll check the TPS out tomarrow. Am I testing for voltage like in the tsrm or are you talking about something physical when you say flat spot?

Test as per TSRM.
http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=101

 

[3p141592654]

He means to make sure that the resistance across the TPS terminals VTA and E2 varies smoothly as the throttle is opened. The TPS tends to wear out in the position the throttle spends most of its time which for most people is just off idle.

To rule out the tranny, monitor the lockup solenoid wire SL going to the tranny (On Supras its Red-Blue from ECT then switches to Red-Black on way to tranny connectors under intake) . You should see the command to lockup be issued by the ECT if the electronics are good (0Volt is off, 12V is on).

 

[3p141592654]

Some additional info on backwards compatibility of T-IV (aka 3309) from Saab. looks to be okay to use in the A340E, but it is not a synthetic. I've also attached a TSB from Mazda on 3309 ATF listing compatible alternatives.

"The fluid used in this transmission system is a completely new type due to the increased stress caused by the slipping lock-up. The fluid is designated JWS 3309, (Aisin-AW spec). JWS 3309 is a mineral-based ATF with unique additives, high coefficient of friction and very high resistance to thermal oxidation. This fluid is factory standard on model -02 cars and applies also to 9-3 (4-speed aut.). JWS 3309 will mix with Dexron II and III. (JWS 3309 is therefore "backwards compatible" but will not provide any advantages over standard fluid in earlier 4-speed automatic transmissions. However, only JWS 3309 is to be used in Aisin AW 33/5 and no other fluid.)"